The proposed projects include (1) The continued correlation of vessel wall dimensions and stresses with their chemical composition, including elastin, collagen, smooth muscle and mucopolysaccharides, with particular emphasis on the human coronary vessels and aorta during growth and aging, (2) the continued use of experimental hypertension as a model for study of factors (mechanical and hormonal) which influence cellular proliferation and fibrous protein synthesis in the vessel wall, (3) exploration of the response of mesenchyme to a controlled mechanical and/or hormonal environment using implanted pulsatile systems.